Recently, five tactile representations were demonstrated in the cerebellar cortex of the rat by Shambes et al. These five separate representations cover a large area of cerebellum and are chiefly devoted to the face and mouth. The different organization of each suggests that they have individual significance in certain behavioral sequences. The anatomical connections are not known. In the present study, the horseradish peroxidase-retrograde tracing technique was used which allows the identification of distant nerve cell bodies with axons terminating in the cerebellum. The results demonstrate that the trigeminal input to cerebellum comes only from the principal and interpolar nuclei. In addition, it appears that the trigeminal input to cerebellum, particularly the hemisphere, is much more extensive than previously realized. These data suggest that the trigemino-cerebellar system will be found to play a major role in facial and oral behavioral sequences.